1. Field of the Invention
The present invention relates to a liquid crystal display device to be used for television and other display apparatuses, to a method of fabricating the same and, more particularly, to a liquid crystal display device that uses a liquid crystal material containing a photosensitive material and a method of fabricating the same.
2. Description of the Related Art
A liquid crystal display device is a display device that comprises a liquid crystal sealed between two opposing substrates and that uses electrical stimulus for optical switching by exploiting the electro-optical anisotropy of a liquid crystal. Utilizing the refractive index anisotropy that the liquid crystal possesses, the brightness of the light transmitted by the liquid crystal panel is controlled by applying a voltage to the liquid crystal and thereby reorienting the axis of the refractive index anisotropy.
In such a liquid crystal display device, it is extremely important to control the alignment of liquid crystal molecules when no voltage is applied to the liquid crystal. If the initial alignment is not stable, when a voltage is applied to the liquid crystal, the liquid crystal molecules do not align in a predictable manner, resulting in an inability to control the refractive index. Various techniques have been developed to control the alignment of liquid crystal molecules, representative examples including a technique that controls the initially formed angle (pretilt angle) between the alignment film and the liquid crystal and a technique that controls the horizontal electric field formed between the bus line and the pixel electrode.
The same can be said of a display device that uses a liquid crystal material containing a photosensitive material; specifically, in a liquid crystal display mode in which the initial alignment is controlled by radiation of light in the presence of an applied voltage, the voltage application method during the radiation becomes important. The reason is that, if the magnitude of the applied voltage differs, a change will occur in the initially formed pretilt angle, resulting in a change in transmittance characteristics.
In connection with a first aspect of the invention, techniques called passive matrix driving and active matrix driving have usually been used to drive liquid crystals; nowadays, with an increasing demand for higher resolution, the active matrix display mode that uses thin-film transistors (TFTS) is the dominant liquid crystal display mode. In a liquid crystal display having such TFTs, when radiating light onto the liquid crystal while applying a voltage to it, it is usually practiced to expose the liquid crystal to light radiation while applying a TFT ON voltage to each gate bus line and a desired voltage to each data bus line, as shown in FIGS. 1 and 2.
However, when such a liquid crystal exposure method is employed, if there is a line defect due to a bus line break or short, as shown in FIG. 3, the liquid crystal will be exposed to light when the liquid crystal in the affected area cannot be driven, and a pretilt angle different from that in other areas will be formed in this defect area, resulting in the problem that the brightness in this area differs from the brightness in other areas.
Or, in the TFT channel ON state, a shift in the TFT threshold value can occur due to exposure to ultraviolet radiation, as shown in FIG. 4, resulting in the problem that the region where the TFTS can be driven stably shifts from the desired region.
On the other hand, in connection with a second aspect of the invention, displays using the TN mode have been the predominant type of active matrix liquid crystal display, but this type of display has had the shortcoming that the viewing angle is narrow. Nowadays, a technique called the MVA mode or a technique called the IPS mode is employed to achieve a wide viewing angle liquid crystal panel.
In the IPS mode, liquid crystal molecules are switched in the horizontal plane by using comb-shaped electrodes, but a strong backlight is required because the comb-shaped electrodes significantly reduce the numerical aperture. In the MVA mode, liquid crystal molecules are aligned vertically to the substrates, and the alignment of the liquid crystal molecules is controlled by the use of protrusions or slits formed in a transparent electrode (for example, an ITO electrode). The decrease in the effective numerical aperture due to the protrusions or slits used in MVA is not so large as that caused by the comb-electrodes in IPS, but compared with TN mode displays, the light transmittance of the liquid crystal panel is low, and it has not been possible to employ MVA for notebook computers that require low power consumption.
When fine slits are formed in the ITO electrode, the liquid crystal molecules tilt parallel to the fine slits, but in two different directions. If the fine slits are sufficiently long, liquid crystal molecules located farther from a structure such as a bank that defines the direction in which the liquid crystal molecules tilt are caused to tilt randomly in two directions upon application of a voltage. However, the liquid crystal molecules located at the boundary between the liquid crystal molecules caused to tilt in different directions, cannot tilt in either direction, resulting in the formation of a dark area such as that shown in FIG. 29. Further, in a structure where the liquid crystal molecules are caused to tilt in two different directions in order to improve viewing angle, if there are liquid crystal molecules that are caused to tilt in the opposite direction, as shown in FIG. 29, the viewing angle characteristics degrade.
In connection with a third aspect of the invention, in an LCD (MVA-LCD) in which an N-type liquid crystal is aligned vertically and in which, upon application of a voltage, the molecules of the liquid crystal are caused to tilt in a number of predefined directions by using alignment protrusions or electrode slits, the liquid crystal molecules are almost completely vertically aligned in the absence of an applied voltage, but are caused to tilt in the various predefined directions when a voltage is applied. The tilt directions of the liquid crystal molecules are controlled so that they always make an angle of 45xc2x0 to the polarizer absorption axis, but the liquid crystal molecules as a continuum can tilt in a direction intermediate between them. Furthermore, areas where the tilt direction of the liquid crystal molecules is displaced from the predefined direction inevitably exist because of the effects of the horizontal electric field, etc. at the time of driving or irregularities in the structure. In normally black displays where the polarizers are arranged in a crossed Nicol configuration, this means that dark areas appear when the display is driven in the white display state, and the screen brightness thus decreases. To address this problem, in a liquid crystal display device constructed by sandwiching between two substrates a liquid crystal composition containing a photopolymerizable or thermally polymerizable component, there is employed a technique that polymerizes the polymerizable component while applying a voltage, thereby defining the direction in which the liquid crystal molecules tilt in the presence of an applied voltage.
With this technique, however, if the polymerization is insufficient, image sticking can occur. This is believed to occur because the rigidity of the polymerized polymer is insufficient and deformation occurs due to the realignment of the liquid crystal molecules at the time of voltage application. On the other hand, to sufficiently polymerize the polymer, the duration of light radiation must be increased, but in that case, takt time at the time of volume production becomes a problem.
In connection with a fourth aspect of the invention, conventional liquid crystal display devices predominantly use the TN mode in which horizontally aligned liquid crystal molecules are twisted between the top and bottom substrates, but gray-scale inversion occurs in the mid gray-scale range because the tilt angle of the liquid crystal differs depending on the viewing direction, that is, the viewing angle. To address this, a technique called the MVA mode has been proposed in which vertically aligned liquid crystal molecules are tilted symmetrically in opposite directions to compensate for the viewing angle. In this technique, alignment control members made of an insulating material are formed on electrodes to control the liquid crystal tilt directions. However, since the liquid crystal molecules tilt in 180xc2x0 opposite directions on both sides of each alignment control member, a dark line is formed and transmittance decreases. To obtain sufficient transmittance, it is preferable to reduce the area occupied by the alignment control members by forming them spaced farther apart, but this would in turn slow the propagation speed of the tilt, resulting in a slow response speed.
To address this, a technique has been proposed in which a liquid crystal composition containing a polymerizable component is sandwiched between substrates and, while applying a voltage, the polymerizable component is polymerized, thereby defining the tilt direction of the liquid crystal molecules. This achieves a faster response speed while retaining the transmittance.
However, in the case of a liquid crystal display device in which the tilt direction of the liquid crystal molecules is defined by polymerizing the polymerizable component in the liquid crystal while applying a voltage, there arises the problem that display unevenness occurs after the polymerization of the polymerizable component, because of the separation of the liquid crystal and the polymerizable component which occurs when the liquid crystal material is injected at high speed at the initial stage of injection or when there is an abrupt change in speed near a frame edge.
In connection with a fifth aspect of the invention, in a liquid crystal display device, it has traditionally been practiced to control the alignment direction of the vertically aligned panel by a TFT substrate having slits in pixel electrodes and a color filter substrate having insulating protrusions, and it has therefore been necessary to form the dielectric protrusions on one of the substrates. Fabrication of such a liquid crystal display device therefore has involved the problem that the number of processing steps increases.
Furthermore, forming the protrusions within display pixels leads to the problem that the numerical aperture decreases, reducing the transmittance. In view of this, it has been proposed to control the alignment of the liquid crystal molecules by a polymerizable component added in the liquid crystal, in order to achieve multi-domains without using dielectric layer protrusions. That is, the liquid crystal to which the polymerizable component is added is injected into the panel and, while applying a voltage, the polymerizable component is polymerized, thereby controlling the alignment of the liquid crystal molecules.
However, if the polymer composition that defines the alignment direction does not have a sufficient cross-linked structure, the polymer becomes flexible, and its restoring force weakens. If the polymer has such properties, then, when a voltage is applied to the liquid crystal to cause the liquid crystal molecules to tilt, and the liquid crystal is still held in that state, the pretilt angle of the liquid crystal does not return to its initial state even after the applied voltage is removed. This means that the voltage-transmittance characteristic has changed, and this defect manifests itself as a pattern image sticking.
In connection with a sixth aspect of the invention, in an MVA-LCD in which liquid crystals having a negative dielectric anisotropy are vertically aligned, and in which the alignment of the liquid crystal in the presence of an applied voltage is controlled in a number of predefined directions, without using a rubbing treatment but by utilizing the banks or slits formed on the substrates, the LCD provides excellent viewing angle characteristics compared with conventional TN mode LCDs, but there is a disadvantage that white brightness is low and the display is therefore relatively dark. The major reason is that portions above the banks or slits correspond to the boundaries across which the liquid crystal alignment changes, and these portions appear optically dark, reducing the transmittance of white. To improve this, the spacing between the banks or slits should be made sufficiently wide, but in that case, as the number of banks or slits for controlling the liquid crystal alignment decreases, it takes time until the alignment stabilizes, thus slowing the response speed.
To obtain a brighter, faster response MVA panel by alleviating the above deficiency, it is effective to use a technique in which a liquid crystal composition containing a polymerizable component is sandwiched between substrates and, while applying a voltage, the polymerizable component is polymerized, thereby defining the tilt direction of the liquid crystal molecules. For the polymerizable component, a monomer material that polymerizes by ultraviolet radiation or heat is usually used. It has, however, been found that this method has a number of problems associated with display unevenness.
That is, as this method is a rubbing-less method, if there occurs even a slight change in the structure or in electric lines of force, the liquid crystal molecules may not align in the desired direction. As a result, there are cases where a contact hole or the like formed outside the display area disrupts the alignment of the liquid crystal molecules and the disruption affects the alignment of the liquid crystal molecules within the display area, resulting in the formation of an abnormal domain and causing the alignment to be held in that state. Furthermore, if structures that cause such disruptions in liquid crystal molecular alignment are located in the same alignment sub-region, abnormal domains formed from the respective structures are concatenated, forming a larger abnormal domain. This causes the liquid crystal molecules outside and inside the display area to be aligned in directions other than the desired directions, and the polymerizable component is polymerized in that state, resulting in such problems as reduced brightness, slower response speed, and display unevenness. FIG. 44 is a plan view showing a pixel in the prior art. In the pixel shown here, contact holes that cause variations in cell thickness are not located at liquid crystal domain boundaries, and two contact holes are located within the same alignment sub-region. As a result, an abnormal domain is formed in such a manner as to connect the two contact holes and, with the alignment held in this state, the polymerizable component is polymerized, resulting in display performance degradations such as reduced brightness, slower response speed, and display unevenness.
Further, when a metal electrode such as a source electrode or a Cs intermediate electrode is extended into the display pixel, there occurs the problem of reduced numerical aperture, and hence, reduced brightness. Moreover, if an electrode with the same potential as the pixel electrode is extended into the display pixel, this also causes reduced brightness, slower response speed, and display unevenness.
In connection with a seventh aspect of the invention, while conducting studies on the technique in which a liquid crystal composition containing a polymerizable component is sandwiched between substrates and while applying a voltage, the polymerizable component is polymerized, thereby defining the tilt direction of the liquid crystal molecules, the inventor et al. encountered the problem that when the same pattern was displayed for a certain length of time, image sticking occurred in the portion where the pattern was displayed. This is believed to occur because the polymerization is insufficient and the polymer deforms. On the other hand, to sufficiently polymerize the polymer, the duration of light radiation or heating must be increased, but in that case, tact time at the time of volume production becomes a problem.
The present invention aims to solve the above-enumerated problems of the prior art and to provide a method of fabricating a liquid crystal display device which, during fabrication of the liquid crystal display device, controls the alignment of liquid crystal molecules when radiating light onto a liquid crystal composition containing a photosensitive material, and thereby achieves substantially uniform alignment of the liquid crystal molecules and ensures stable operation. The invention also aims to provide such a liquid crystal display device.
To solve the above-enumerated problems, the first aspect of the invention provides methods based on the following three major concepts.
1. Avoid the effects of wiring defects by driving the liquid crystal by applying an AC voltage and using an electrical capacitance.
2. Avoid the effects of wiring defects by holding the wiring lines and electrodes on the second substrate at the same potential.
3. Avoid the effects of wiring defects while screening TFT channel portions from light.
More specifically, based on the first concept, the first aspect of the invention provides
(1) a method of fabricating a liquid crystal display device, comprising:
forming on a first substrate a common electrode for applying a voltage over an entire surface of the substrate;
forming on a second substrate a gate bus line and a data bus line arranged in a matrix array, a thin-film transistor located at an intersection of the two bus lines, a pixel electrode connecting to the thin-film transistor, and a Cs bus line that forms an electrical capacitance to the pixel electrode;
forming a liquid crystal layer by filling a liquid crystal composition, containing a photosensitive material, into a gap between the first substrate and the second substrate;
forming an electrical capacitance by the common electrode and the pixel electrode by sandwiching the liquid crystal layer therebetween; and
radiating light to the liquid crystal layer while applying an AC voltage between the common electrode and the pixel electrode by applying AC voltages to the common electrode and the Cs bus line.
Based on the second concept, the invention provides
(2) a method of fabricating a liquid crystal display device, comprising:
forming on a first substrate a common electrode for applying a voltage over an entire surface of the substrate;
forming on a second substrate a gate bus line and a data bus line arranged in a matrix array, a thin-film transistor located at an intersection of the two bus lines, a pixel electrode connecting to the thin-film transistor, and a Cs bus line that forms an electrical capacitance to the pixel electrode;
forming a liquid crystal layer by filling a liquid crystal composition, containing a photosensitive material, into a gap between the first substrate and the second substrate;
forming an electrical capacitance by the common electrode and the pixel electrode by sandwiching the liquid crystal layer therebetween;
insulating the common electrode from the three bus lines, or connecting the common electrode to the three bus lines via high resistance; and
radiating light to the liquid crystal layer while applying a DC voltage between the common electrode and the pixel electrode by applying a DC voltage between the common electrode and the three bus lines (the gate bus line, the data bus line, and the Cs bus line) formed on the second substrate, or
(3) a method of fabricating a liquid crystal display device, comprising:
forming on a first substrate a common electrode for applying a voltage over an entire surface of the substrate;
forming on a second substrate a gate bus line and a data bus line arranged in a matrix array, a thin-film transistor located at an intersection of the two bus lines, a pixel electrode connecting to the thin-film transistor, a Cs bus line that forms an electrical capacitance to the pixel electrode, and a repair line intersecting with at least one of the data bus and gate bus lines;
forming a liquid crystal layer by filling a liquid crystal composition, containing a photosensitive material, into a gap between the first substrate and the second substrate;
forming an electrical capacitance by the common electrode and the pixel electrode by sandwiching the liquid crystal layer therebetween; and
radiating light to the liquid crystal layer while applying a DC voltage between the common electrode and the pixel electrode by applying a DC voltage between the common electrode and the four bus lines (the gate bus line, the data bus line, the Cs bus line, and the repair line) formed on the second substrate, or
(4) a method of fabricating a liquid crystal display device, comprising:
forming on a first substrate a common electrode for applying a voltage over an entire surface of the substrate;
forming on a second substrate a gate bus line and a data bus line arranged in a matrix array, a thin-film transistor located at an intersection of the two bus lines, a pixel electrode connecting to the thin-film transistor, and a Cs bus line that forms an electrical capacitance to the pixel electrode;
forming a liquid crystal layer by filling a liquid crystal composition, containing a photosensitive material, into a gap between the first substrate and the second substrate;
forming an electrical capacitance by the common electrode and the pixel electrode by sandwiching the liquid crystal layer therebetween; and
connecting the common electrode, via high resistances, to the three bus lines (the gate bus line, the data bus line, and the Cs bus line,) formed on the second substrate, and radiating light to the liquid crystal layer while applying a DC voltage between the common electrode and the pixel electrode by applying a DC voltage between the common electrode and at least one of the bus lines.
Based on the third concept, the invention provides
(5) a method of fabricating a liquid crystal display device, comprising:
forming on a first substrate a common electrode for applying a voltage over an entire surface of the substrate;
forming on a second substrate a gate bus line and a data bus line arranged in a matrix array, a thin-film transistor located at an intersection of the two bus lines, a pixel electrode connecting to the thin-film transistor, and a Cs bus line that forms an electrical capacitance to the pixel electrode;
forming a CF resin or a light blocking pattern on a channel portion of the thin-film transistor;
forming a liquid crystal layer by filling a liquid crystal composition, containing a photosensitive material, into a gap between the first substrate and the second substrate;
forming an electrical capacitance by the common electrode and the pixel electrode by sandwiching the liquid crystal layer therebetween;
electrically connecting adjacent data bus lines at both ends thereof; and
radiating light to the liquid crystal layer while applying an AC voltage between the common electrode and the pixel electrode by applying a transistor ON voltage to the gate bus line and an AC voltage between the common electrode and the data bus line, or
(6) a method of fabricating a liquid crystal display device, comprising:
forming on a first substrate a common electrode for applying a voltage over an entire surface of the substrate;
forming on a second substrate a gate bus line and a data bus line arranged in a matrix array, a thin-film transistor located at an intersection of the two bus lines, a pixel electrode connecting to the thin-film transistor, a Cs bus line that forms an electrical capacitance to the pixel electrode, and a repair line intersecting with the data bus line;
forming a CF resin or a light blocking pattern on a channel portion of the thin-film transistor;
forming a liquid crystal layer by filling a liquid crystal composition, containing a photosensitive material, into a gap between the first substrate and the second substrate;
forming an electrical capacitance by the common electrode and the pixel electrode by sandwiching the liquid crystal layer therebetween;
connecting at least one data bus line with at least one repair line by laser radiation or another method; and
radiating light to the liquid crystal layer while applying an AC voltage between the common electrode and the pixel electrode by applying a transistor ON voltage to the gate bus line and an AC voltage between the common electrode and the data bus line and repair line (the repair line is at the same potential as the data bus line).
In the second aspect of the invention, there is provided
(7) a method of fabricating a vertical alignment liquid crystal display device, comprising:
forming a liquid crystal layer by filling a liquid crystal composition into a gap between two substrates each having a transparent electrode and an alignment control film for causing liquid crystal molecules to align vertically, the liquid crystal composition having a negative dielectric anisotropy and containing a polymerizable monomer; and
polymerizing the monomer while applying a voltage between opposing transparent electrodes, and thereby providing a pretilt angle to the liquid crystal molecules, and wherein:
before polymerizing the monomer, a constant voltage not smaller than a threshold voltage but not greater than a saturation voltage is applied between the opposing transparent electrodes for a predetermined period of time, and thereafter, the voltage is changed to a prescribed voltage and, while maintaining the prescribed voltage, ultraviolet radiation or heat is applied to the liquid crystal composition to polymerize the monomer.
That is, when polymerizing the polymerizable monomer, a voltage slightly higher than the threshold voltage is applied and, after the liquid crystal molecules are tilted in the right direction, the voltage is raised to a higher level; then, while maintaining the voltage at the higher level, the polymerizable monomer is polymerized.
In the third aspect of the invention, there is provided
(8) a method of fabricating a liquid crystal display device, comprising:
forming a liquid crystal layer by filling a liquid crystal composition containing a polymerizable monomer into a gap between two substrates each having a transparent electrode; and
polymerizing the monomer while applying a voltage between opposing transparent electrodes, and thereby providing a pretilt angle to liquid crystal molecules while, at the same time, controlling the direction in which the liquid crystal molecules tilt in the presence of an applied voltage, and wherein:
light radiation for polymerizing the polymerizable monomer is performed in at least two steps.
In the fourth aspect of the invention, there is provided
(9) a liquid crystal display device in which a liquid crystal composition containing a photopolymerizable or thermally polymerizable component is sandwiched between substrates and the polymerizable component is photopolymerized or thermally polymerized while applying a voltage, thereby defining the direction in which liquid crystal molecules tilt in the presence of an applied voltage, wherein a plurality of injection ports for injecting therethrough the liquid crystal composition containing the polymerizable component are formed in one side of the liquid crystal display device, and spacing between the respective injection ports is not larger than one-fifth of the length of the side in which the injection ports are formed, or
(10) a liquid crystal display device in which a liquid crystal composition containing a photopolymerizable or thermally polymerizable component is sandwiched between substrates and the polymerizable component is polymerized while applying a voltage, thereby defining the direction in which liquid crystal molecules tilt in the presence of an applied voltage, wherein a cell gap in a frame edge BM area is not larger than the cell gap of a display area, or
(11) a liquid crystal display device in which a liquid crystal composition containing a photopolymerizable or thermally polymerizable component is sandwiched between substrates and the polymerizable component is polymerized while applying a voltage, thereby defining the direction in which liquid crystal molecules tilt in the presence of an applied voltage, wherein a main seal or an auxiliary seal is formed in a frame edge BM area to eliminate a cell gap in the frame edge BM area, or
(12) a liquid crystal display device in which a liquid crystal composition containing a photopolymerizable or thermally polymerizable component is sandwiched between substrates and the polymerizable component is polymerized while applying a voltage, thereby defining the direction in which liquid crystal molecules tilt in the presence of an applied voltage, wherein an auxiliary seal is formed so that a material whose concentration of the polymerizable material relative to liquid crystal is abnormal is guided into a BM area.
In the fifth aspect of the invention, there is provided
(13) a method of fabricating a liquid crystal display device, comprising:
forming a common electrode and a color filter layer on a first substrate;
constructing a second substrate from an array substrate on which are formed a gate bus line layer, a gate insulating film layer, a drain bus line layer, a protective film layer, and a pixel electrode layer;
forming fine slits in the pixel electrode layer in such a direction that a pixel is divided by the slits into at least two sub-regions;
forming on each of the two substrates a vertical alignment film for vertically aligning liquid crystal molecules;
forming a liquid crystal layer by filling an n-type liquid crystal composition having a negative dielectric anisotropy into a gap between the two substrates, the liquid crystal composition containing an ultraviolet curable resin having a liquid crystal backbone;
radiating ultraviolet light while applying to the liquid crystal molecules a voltage not smaller than a threshold value of the liquid crystal molecules, thereby defining the direction in which the liquid crystal molecules tilt in the presence of an applied voltage; and
arranging two polarizers on top and bottom surfaces of the liquid crystal display device in a crossed Nicol configuration with the absorption axes thereof oriented at an angle of 45 degrees to the alignment directions of the liquid crystal molecules.
In the sixth aspect of the invention, there is provided
(14) a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes, and a pretilt angle of liquid crystal molecules and a tilt direction thereof in the presence of an applied voltage are controlled by using a polymer that polymerizes by heat or light radiation, wherein any portion where cell thickness varies by 10% or more due to design constraints is located at a liquid crystal domain boundary, or
(15) a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes, and a pretilt angle of liquid crystal molecules and a tilt direction thereof in the presence of an applied voltage are controlled by using a polymer that polymerizes by heat or light radiation, wherein a contact hole that connects between a source electrode and a pixel electrode is formed at a liquid crystal domain boundary, or
(16) a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes, and a pretilt angle of liquid crystal molecules and a tilt direction thereof in the presence of an applied voltage are controlled by using a polymer that polymerizes by heat or light radiation, wherein a contact hole that connects between a Cs intermediate electrode and a pixel electrode is formed at a liquid crystal domain boundary, or
(17) a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes, a pretilt angle of liquid crystal molecules and a tilt direction thereof in the presence of an applied voltage are controlled by using a polymer that polymerizes by heat or light radiation, and liquid crystal alignment is divided between two or more sub-regions, wherein more than one portion where cell thickness varies by 10% or more due to design constraints does not exist, or
(18) a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes, a pretilt angle of liquid crystal molecules and a tilt direction thereof in the presence of an applied voltage are controlled by using a polymer that polymerizes by heat or light radiation, and liquid crystal alignment is divided between two or more sub-regions, wherein more than one contact hole is not formed in the same sub-region, or
(19) a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes, and a pretilt angle of liquid crystal molecules and a tilt direction thereof in the presence of an applied voltage are controlled by using a polymer that polymerizes by heat or light radiation, wherein a pixel electrode, a source electrode, and a Cs intermediate electrode are connected by a single contact hole, or
(20) a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes, and a pretilt angle of liquid crystal molecules and a tilt direction thereof in the presence of an applied voltage are controlled by using a polymer that polymerizes by heat or light radiation, wherein a metal electrode is wired along a liquid crystal domain boundary within a display pixel, or
(21) a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes, and a pretilt angle of liquid crystal molecules and a tilt direction thereof in the presence of an applied voltage are controlled by using a polymer that polymerizes by heat or light radiation, wherein an electrode having the same potential as a pixel electrode is not wired in a slit portion of the pixel electrode within a display pixel.
In the seventh aspect of the invention, there is provided a
(22) a method of fabricating a liquid crystal display device, comprising: forming a liquid crystal layer by filling a liquid crystal composition containing a polymerizable monomer into a gap between a pair of substrates having electrodes; and polymerizing the monomer by radiating ultraviolet light to the liquid crystal composition while applying a prescribed liquid crystal driving voltage between opposing electrodes, and wherein: after polymerizing the monomer, additional ultraviolet radiation is applied to the liquid crystal composition without applying the liquid crystal driving voltage or while applying a voltage of a magnitude that does not substantially drive the liquid crystal.